/Engine/Plugins/Runtime/MeshModelingToolset/Source/ModelingComponents/Public/Selection/GeometrySelectionVisualization.h
Update the geometry selection preview geometry according to Settings. Call this in your tool OnTick function
namespace UE { namespace Geometry { void UE::Geometry::UpdateGeometrySelectionVisualization ( [UPreviewGeometry](API\Plugins\ModelingComponents\Drawing\UPreviewGeometry) * PreviewGeom, [UGeometrySelectionVisualizationProperties](API\Plugins\ModelingComponents\PropertySets\UGeometrySelecti-) * Settings ) } }